r600g: Silence uninitialized variable warnings.
r600g: Silence uninitialized variable warnings.

Fixes these GCC warnings.
r600_shader.c: In function 'tgsi_tex':
r600_shader.c:1611: warning: 'src2_chan' may be used uninitialized in this function
r600_shader.c:1611: warning: 'src_chan' may be used uninitialized in this function

dellis1972/glsl-optimizer,dellis1972/glsl-optimizer,KTXSoftware/glsl2agal,zz85/glsl-optimizer,metora/MesaGLSLCompiler,jbarczak/glsl-optimizer,bkaradzic/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,djreep81/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,zeux/glsl-optimizer,metora/MesaGLSLCompiler,wolf96/glsl-optimizer,KTXSoftware/glsl2agal,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,mapbox/glsl-optimizer,djreep81/glsl-optimizer,wolf96/glsl-optimizer,mcanthony/glsl-optimizer,tokyovigilante/glsl-optimizer,mapbox/glsl-optimizer,bkaradzic/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,jbarczak/glsl-optimizer,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,adobe/glsl2agal,benaadams/glsl-optimizer,KTXSoftware/glsl2agal,zz85/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,KTXSoftware/glsl2agal,zz85/glsl-optimizer,tokyovigilante/glsl-optimizer,tokyovigilante/glsl-optimizer,adobe/glsl2agal,bkaradzic/glsl-optimizer,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,adobe/glsl2agal,metora/MesaGLSLCompiler,zeux/glsl-optimizer,djreep81/glsl-optimizer,adobe/glsl2agal,benaadams/glsl-optimizer,KTXSoftware/glsl2agal,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,adobe/glsl2agal,benaadams/glsl-optimizer,jbarczak/glsl-optimizer